The subject matter disclosed herein relates generally to fluid fittings, and more particularly, to embodiments of a fluid fitting that are configured to measure properties of fluids in harsh, caustic environments such as the environment in a fuel system.
There are many devices that can measure the properties of fluids. These devices include the fittings and couplings (hereinafter “fittings”) that are used to secure, and in some cases restrain, the hoses, pipes, and lines which carry the fluid between two points. These fittings may incorporate devices such as sensors that are particularly responsive to one or more of the properties of the fluid. Temperature sensors, pressure sensors, and the like are all suitable devices that can be incorporated as part of the fitting. Certain applications, however, require that the fittings have special construction, which can withstand the physical and chemical rigors imposed by the fluid environment. These environments can include, for example, fuel carrying and distribution systems that are typically found in automobiles.
While fittings have been developed that can monitor the fuel and other fluids in these systems, few of these fittings can incorporate semiconductor die and similar devices such as ceramic and similar capacitive devices. In one example, techniques that use epoxy to secure such devices to a metal or plastic component are inadequate because the epoxy can fail due to the thermal cycling and/or pressure cycling inherent in the automotive environments. The epoxy, as well as the other materials of construction, can also breakdown due to exposure to the caustic chemical properties of the fluid in the fuel system. Furthermore, it has also been found that residual stresses can be induced in the devices themselves by the epoxy during the curing/adhesion processes. These stresses can require additional mitigating steps to compensate for deviations in the measurements by the device.
In another example, some fittings that are used to measure fluid pressure in a pipe can incorporate such ceramic capacitive circuits as circuits that are printed on stainless steel foil. This approach requires that the fitting comprise a large stainless steel housing, as well as a threaded connector and brazed joint for securing the housing to the pipe. This construction makes the overall package bulky, a problem for the automotive environments because the larger components in the fuel system significantly increase the risk of damage in a crash scenario. Moreover, due to the space constraints in the automobile engine compartment, the use of such large monitoring fittings may require changes to the components, design, and sheet metal of the vehicle.
Still other examples of fittings for measuring fluid properties are susceptible to electrostatic discharge (“ESD”). That is, such fittings are constructed of conductive materials that, while compatible with the particular fluid of the system, can permit charge to build up at least within and around the fluid pathway. These fittings often discharge the built-up charge with external hardware, e.g., grounding straps. This hardware, however, can generally hinder application and use of the fitting in the environments discussed above.
Therefore, it would be advantageous to provide a fitting that can measure properties of the fluid, but that is designed and manufactured for robust, and varied applications. It would also be advantageous, for example, to provide a fitting that can be operatively configured to be installed, removed, and re-installed easily, and quickly during manufacturing, production, and service of, e.g., automobiles and automobile fuel systems. Moreover, such fittings could provide other advantages are needed that can withstand caustic environments, dissipate electrical charge, and provide reliable, platform technology for monitoring a variety of properties of the fluids in these systems, while being constructed in a manner that meets the cost, size, and other constraints of the automotive industry.